Anyway, I've posted a rendering of how spread is expected to work, for it's "normal" interpretation:
http://www.bradclicks.com/cssplay/spread-sample.png
I think that if a radius was calculated based on where the straight parts ended (offset directly from where they were before the spread) then that should be fine too. I started to do a rendering of that too, but it was almost identical on the big gray shape, so I don't think anyone would complain (especially since there will typically be blur too). For the inner shadow spread or for negative spread (aka "choke"), it might even look better, smoothing out the weird corner joins that can happen as in this example (upper left corner), when one dimension of the ellipse loses its roundness before the other.
On Apr 29, 2010, at 5:00 PM, Alex Meiburg wrote:
> This makes it even worse, I feel. It's not an ellipse or a circle. It's something else, construed only from unusual rules. The only reason people haven't be arguing about blurs (I think someone already said this) is because they're largely up to the user agent. That doesn't mean they won't suffer from the same problems. I think anything that's decided for the spread should immediately be applied to the shadow as well, just because it isn't doesn't mean the spread should do what the shadow does.
>
> ~6 out of 5 statisticians say that the number of statistics that either make no sense or use ridiculous timescales at all has dropped over 164% in the last 5.62474396842 years.
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> On Wed, Apr 28, 2010 at 8:16 PM, Brad Kemper <brad.kemper@gmail.com> wrote:
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> On Apr 28, 2010, at 6:40 PM, Alex Meiburg wrote:
>
> > Then, the shadow would add something like 5px to each radius
>
> No, it just follows the radius in the same way that it follows the straight parts. So does the blur, for that matter. For instance, take a look at this, where you can see the difference between a sharp corner and a heavily blurred one (no spread in either):
>
> http://www.bradclicks.com/cssplay/Blur-vs-Corner.html
>
> Now look at this image, where the white has been changed to yellow, so that you can clearly see the extent of the blurred area:
>
> http://www.bradclicks.com/cssplay/Blur-vs-Corner_result.png
>
> This shows that the blur area has extended the boundary of the shadow out 25px, and created a shape with a 50px corner radius! Yet no one is complaining about how it increases the radius from 0 to 50px. This is the same sort of thing that spread does, but with a solid colored brush instead of a fuzzy-edged brush. In fact it is what 'border' does too, but no one complains about it having inner radii that are different from the outer radii. Border is more like inner shadow, in that the radius of the inner part gets smaller than the specified part, but that's just because the spec says to apply the radius to the outside of the border instead of the inside. It could just as easily have gone the other way.
>